Industrial implementation of a controlled sensorless synchronous drive with hard start conditions

The subject of this paper is a synchronous drive of grinding ball mills 4 MW, 150 rpm, 6 kV, 50 Hz on the base of PWM CSI. The system is installed at the concentrating plant of Norilsknickel in Russia. Specific to this drive is large stalling torque-up to 125% of rated torque. This is a sensorless drive. Another specific feature is the necessity of synchronization with power system and switching to power system. The converting-regulating device of this drive isn´t designed for hard work conditions. It uses simplified control algorithms. This caused the main difficulties of implementation. Simulation was performed before drive commissioning. It provided reliance in successful results of the project and expedient values for most programmable parameters. The main result was that it is possible to choose such acceleration of current vector in infra-low speed zone that provides necessary torque with suitable speed oscillations. Results of simulation were used while commissioning the drive. The drive operates successfully with settings of parameters that were defined by simulation. The main features of the drive are presented in paper.